Hi GDAL Dev's,
I'd like to use a OGR SQL statement to filter features from a shapefile
based on their area. e.g. keep only the large lakes in a water layer for
instance.
A simple way to allow this would be to add a new OGR_GEOM_AREA special
field on OGRFeatures that calls the OGRSurface::getArea() method and
would be handled similar to the OGR_GEOM_WKT and other special fields in
OGRFeature::GetFieldAsString?().
Another option could be to add operators on geometries in the SQL parser
but that could be a bit more involved (e.g. "select ST_Area(geom) from
...").
I have created a ticket about this which includes a patch for the new
OGR_GEOM_AREA special field:
http://trac.osgeo.org/gdal/ticket/2949
What would you think of adding this to the SVN trunk? Or can anyone
provide hints on the way to implement operators on geometries since that
would clearly be a better solution but I'm not clear on the best way to
add this to the OGR SQL engine.
Daniel
--
Daniel Morissette
http://www.mapgears.com/
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